This invention relates to the conversion of energy from naturally occurring sources of mechanical energy, and particularly to the conversion of mechanical energy present in flowing water to useful energy.
While not limited thereto, the invention has particular utility for the generation of relatively small amounts of power for use in small devices intended for long life in inaccessible locations. For example, to perform long endurance military missions, small unattended sensors or robots need more electrical power to sense, communicate, or move than they can practically carry in a precharged power storage device. This means that they must be able to harvest energy from their environment during the mission to periodically re-charge their power sources. The small size of the devices typically used in military systems makes it difficult to collect a useful amount of power since natural energy usually occurs as a xe2x80x9cfluxxe2x80x9d, and the amount available for collection depends on the physical capture area. Thus, there is a need for a small, highly reliable family of power generators that efficiently convert environmental energy into electrical power. This need is satisfied according to the present invention.
A power generator, particularly useful for collecting power from flowing fluids, comprises an elongated, eel-like structure for being disposed within a flowing fluid for causing energy generating eel-like or sinuous undulations or flutterings along the length of the structure. In a preferred embodiment, the structure comprises an elongated, central layer of a flexible material providing a common support for a plurality of separate energy generating elements spaced along opposite sides of the support. Each element comprises a length of a flexible and preferably plastic-like piezoelectric material (which can be part of a continuous sheet of the material) having electrodes on opposite sides thereof forming a capacitor for collecting electric power generated by the elements. For inducing turbulence in the flowing fluid (if not already present) for more efficient mechanical coupling of the fluid to the structure, the structure is disposed downstream of a vortex generating xe2x80x9cbluff bodyxe2x80x9d which, in one embodiment, is a flat plate disposed transversely in the path of the fluid flow for generating vortices at the plate edges. The vortices induce undulations in the downstream structure.